Raid: Kazakoemaru

Boss Statistics

Active Buff		Increases resistance to Quick cards by 50%
Skills		Decreases debuff resistance of enemy team by 20% for 3 turns
NP Effect		Deals around 6000-6500 damage to all opponents and seals NP for 1 turn

Sasaki Kojiro Statistics
	HP	20,000 - 600,000
	LVL	30 - 85
	Class	Assassin
	Skills	Has access to all three of his skills
	NP	Swallow Reversal, High ST damage

Battle 1/2	20,000 Lesser Oni	20,000 Lesser Oni	20,000 Lesser Oni
Fatal Battle 2/2	6,000,000 Kazakoemaru		600,000 Sasaki Kojiro

Do not forget: Exploit wave 1 to generate as much NP gauge as possible.
Sasaki Kojirou may have type advantage over the main DPS.
Build your team to counter Kazakoemaru, the common casters supports will help counter Sasaki Kojirou. If struggling to deal with him in time, Medea can make short work of him and can be swapped out with the Order Change from the Chaldea Combat Uniform.
Sasaki Kojirou has a short charge bar, so try and take him out quickly before he has time to NP one of your team members.
Kazakoemaru’s skill is harmless. The NP gauge seal on his NP can be annoying though.
Try to drain Kazakoemaru’s NP bar or disable him once with a full NP bar. This will result in one less NP over 15 turns.
The main difficulty is dealing enough damage in time to clear the full HP bar early on in Onigashima. Fielding non-quick Rider and event Berserker Servants is ideal, but even Quick-based Riders can still deal good damage to Kazakoemaru.
Using the Bean consumables will really help out early on and also help reduce risk while getting a feel for the damage output of each raid.

Try to field set-ups with two Servants that provide offensive buffs for one main DPS with Golden Sumo equipped.
But don’t leave the main DPS entirely undefended, especially if the DPS is a Berserker.
Ideally, a set-up would be Main DPS / Support / Offensive Hybrid or Main DPS / Support / Support.
Field additional Supports or Hybrids in the backline as generally the Main DPS will not fall first.
If in doubt, the Chaldea Combat Uniform is a safe option and can help delay Sasaki Kojirou from NPing a Servant.